Sewage is one type of wastewater. Sewage collection and disposal is usually done via a system of sewer pumps (sewers) called sewerage, and sometimes via a cesspool emptier. Sewage treatment is usually done with electric, sumersible and other tyoes of pumps.
Drainage is the natural or artificial removal of surface and sub-surface water from a given area. Many agricultural soils need drainage to improve production or to manage water supplies.
Why DRAINAGE is so important: Wetland soils may need drainage to be used for agriculture. In moist climates, soils may be adequate for cropping with the exception that they become waterlogged for brief periods each year, from snow melt or from heavy rains. Soils that are predominantly clay will pass water very slowly downward, meanwhile plant roots suffocate because the excessive water around the roots eliminates air movement through the soil.
Drainage is especially important in tree fruit production. In each of these cases appropriate drainage is used to carry off temporary flushes of water to prevent damage to annual or perennial crops. In farming drier areas, irrigation is often used, and one would not consider drainage necessary. Irrigated land may need periodic flushes with excessive irrigation water and drainage to remove these toxic minerals.
Drainage in Construction
The civil engineer or site engineer is responsible for drainage in construction projects. They set out from the plans all the roads, drainage, culverts and sewers involved in construction operations. During the construction of the work on site he/she will set out all the necessary levels for each of the previously mentioned factors. Site engineers work alongside architects and construction managers, supervisors, planners, quantity surveyors, the general workforce, as well as subcontractors.